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71.
本文从倾斜象片与水平象片的透视关系出发,考虑A_8精密立体测图仪的转角系关,导出了模拟计算机比例尺缩放和影象旋转改正公式和实际运算公式,进而阐述了PPO-8正射投影装置是如何实现对ZOOM系统和DOVE系统两个基本公式的控制。 相似文献
72.
提出了一种基于多图形处理器(graphic processing unit,GPU)设计思想的Harris角点检测并行算法,使用众多线程将计算中耗时的影像高斯卷积平滑滤波部分改造成单指令多线程(single instruction multi-ple thread,SIMT)模式,并采用GPU中共享存储器、常数存储器和锁页内存机制在统一计算设备架构(com-pute unified device archetecture,CUDA)上完成影像角点检测的全过程。实验结果表明,基于多GPU的Har-ris角点检测并行算法比CPU上的串行算法可获得最高达60倍的加速比,其执行效率明显提高,对于大规模数据处理呈现出良好的实时处理能力。 相似文献
73.
为了提高我国卫星导航系统GEO卫星定轨能力,针对我国卫星导航系统所特有的新数据和新方法,利用CAPS系统的C波段转发式测距数据进行了单GEO卫星定轨实验.在分析该方法技术特点的基础上,从定轨残差和轨道重叠弧段比较等方面,对定轨结果进行了分析.由于设备转发时延是影响该方法定轨精度的重要因素,因此同时还分析了系统偏差对定轨精度的影响,得出了一些有益的结论. 相似文献
74.
A model test system with a dynamic load device for geotechnical engineering in cold regions is presented. This system consists of
a model test tank, a refrigeration device and temperature controller, a dynamic load device, together with sensors and data loggers
for detecting stress, deformation, and temperature changes. The system can accommodate soil blocks up to 3 m in length, 2.5 m in
width, and 1 m in height. The lowest temperature provided by the refrigeration device is -20 °C. The maximum load provided by
the dynamic load device is 100 kN and the vibration frequency of the dynamic load can range from 0.1 to 10 Hz. A number of
waveforms, such as sine waves, rectangular waves, triangle waves, and other user-defined waves can be generated by the dynamic
load device controller. 相似文献
75.
Rumjana Mitzeva Boryana Tsenova Rachel Albrecht Walt Petersen 《Atmospheric Research》2009,91(2-4):299-309
Two different thunderstorms are simulated by two distinct one-dimensional cloud models using four different parameterisations of the non-inductive mechanism of electric charging, based on laboratory studies. The results demonstrate that during the early (pre-lightning) stage of thunderstorm electrification, simulated charge density depends not only on the model charging parameterisation employed, but also on the specific representations of the kinematics and microphysical characteristics of the model itself. Though no conclusions are drawn regarding the physical suitability of the charging parameterisations themselves, the analysis indicates that the most significant differences between the simulated charge structures of the clouds produced in each particular model are the result of different distributions of model cloud characteristics and of the type of parameterisation of the microphysical processes. The study reveals that it is too early to make any conclusion regarding which, if any, of the existing parameterisation schemes are better suited to the realistic simulation of electrical charging in real clouds. 相似文献
76.
77.
Conventional RC/TS (resonant column and torsional shear) devices use a specimen with an aspect ratio (height-to-diameter) of 2:1 and this generates a maximum shear strain in the sample of about 1.5% at the maximum rotation of the driving system. The objective of this study is to modify the RC/TS device to generate higher strain amplitude. The modifications include a new base pedestal to overcome the limitations in the travel of the drive system and modification of the coil wiring to increase torque. The effects of the new coil wire on torque in the electromagnetic drive system were evaluated and the application of the modified device was illustrated using sand soil. 相似文献
78.
Stress Measurement by Overcoring at Shallow Depths in a Rock Slope: the Scattering of Input Data and Results 总被引:1,自引:0,他引:1
C. Clément V. Merrien-Soukatchoff C. Dünner Y. Gunzburger 《Rock Mechanics and Rock Engineering》2009,42(4):585-609
This paper describes a field experiment of stress measurement using the overcoring method performed in a rock slope, called
Rochers de Valabres (located in France’s Southern Alps Region), a field laboratory site prone to rockfalls. Six measurements were conducted at
shallow depths from the surface, moving deeper along a sub-horizontal borehole. The experiment was conducted in heterogeneous
and anisotropic gneiss, with the overcored rock elastic properties, as evaluated by biaxial and uniaxial tests, being widely
scattered. Since stress calculations are sensitive to all input data uncertainties, strain inversion was, thus, performed
using an experimental device and Monte Carlo simulations. The experimental device allows the assessment of rather broad confidence
intervals for both stress magnitude and orientation. The results indicate that the stress state in the surface area is quite
heterogeneous and may be correlated with topography. The measurements show a nonlinear stress distribution with distance to
the free surface, along with high values of principal stresses, despite the vicinity of the surface. Although influenced by
local topography, orientations of the principal computed stresses are characterized by a high turnover due to local heterogeneities.
The results are roughly in accordance to a 2D finite element model of the site. 相似文献
79.
在钻探施工过程中,由于工程要求,必须对钻孔做孔口压水试验,根据钻孔吸水量、压力数据,检验钻孔的漏失及其他情况。传统孔口压水试验使用的孔口装置,必须把孔内钻具提出孔外,严重地影响工程施工进度。分体式不提钻钻孔压水试验孔口装置的研发,可在不提钻的情况下完成孔口压水试验作业,大幅度缩短施工工期,减轻工人的劳动强度,减少安全事故的发生,对钻探工程施工具有一定的经济价值和现实意义。本文详细介绍了研制的分体式不提钻钻孔压水试验孔口装置的结构、工作原理及使用方法,并与传统孔口压水装置进行了试验对比,验证了分体式不提钻孔口压水试验孔口装置工作的可靠性及优势。 相似文献
80.
日照万泽丰渔业有限公司黄海冷水团优质鱼类绿色养殖项目是山东省首批公布的新旧动能转换重大项目,规划海域面积20 km2。工程勘察是工程建设项目首先开展的基础性工作,是项目选址、设计和施工的重要依据。本文通过有效盘活有限资源,科学论证、严谨施工,创新钻探船改造、重力导向装置实现深海套管安放,成功实施了该项目的工程勘察工作,为远海深水勘察施工提供了经验。 相似文献